Fuel compositions for vehicles are continually being improved to enhance various properties of the fuels in order to accommodate their use in newer, more advanced engines including direct injection gasoline engines. Accordingly, fuel compositions typically include additives that are directed to certain properties that require improvement. For example, friction modifiers, such as fatty acid amides, are added to fuel to reduce friction and wear in the fuel delivery systems of an engine. When such additives are added to the fuel rather than the lubricant, a portion of the additives are transferred into the lubricant in the engine piston ring zone where it may reduce friction and wear and thus improve fuel economy. While such additives may be beneficially added to the lubricant rather than the fuel, such additive are not effective for improving lubricity and reducing wear in fuel delivery systems when added to the lubricant. Such fuel additives may be passed into the oil sump during engine operation, so that a fuel additive that is also beneficial to the engine lubricant is desirable. However, certain fatty amides may be unstable in additive packages for fuels at low storage temperatures and the performance of such fatty acid amides is often less than desirable.
Partial esters of fatty acid and polyhydroxy alcohols such as glycerol monooleate (GMO) are known as friction modifiers for lubricant compositions. Likewise, diethanolamine fatty amides are also well known friction modifiers. While GMO and fatty amide friction modifiers may improve fuel economy when added to a lubricant, GMO and certain diethanolamine fatty amides may be unstable in additive packages for fuels or may cause an increase in intake valve deposits in gasoline engines. Furthermore, the fuel economy improvement may be less than desirable when using GMO or certain fatty amides in fuel compositions. Accordingly, GMO and fatty amide friction modifiers cannot be beneficially added to a fuel composition to improve the wear protection of the fuel delivery system without harmful and undesirable side effects.
Fatty amine ethoxylates are also known as fuel additives that may reduce fuel consumption. However, such fatty amine ethoxylates are typically derived from natural sources and thus may vary by region and over time. In addition, some fatty amine ethoxylates have a high freezing points or are solids at room temperature and may require heating or the use of a solvent for storage and handling. Lastly, fatty amine ethoxylates typically have poor low temperature compatibility in fuel additive compositions.
Many other friction modifiers have been tried, however there remains a need for a friction modifier that enables a fuel additive packages containing the friction modifier to remain liquid at low temperatures, that is resistant to hydrolysis, that may be readily formulated into a fuel additive packages, that offers good fuel economy benefits, and that provides wear protection to fuel delivery systems, among others characteristics. Accordingly, there continues to be a need for a fuel additive that is cost effective to manufacture and improves multiple characteristics of a fuel.
In accordance with the disclosure, exemplary embodiments provide a fuel additive for a gasoline fuel composition that includes a synergistic mixture of (i) N,N-bis(hydroxyalkyl)-alkylamine, and (ii) an amide reaction product of a hydroxy acid, hydroxy ester or lactone and an amine or ether amine, wherein a weight ratio of (i) to (ii) in the synergistic mixture ranges from about 1:5 to about 5:1.
In another embodiment, there is provided a gasoline fuel composition for reducing fuel system component wear. The fuel composition includes gasoline and a fuel additive mixture of (i) N,N-bis(hydroxyalkyl)-alkylamine, and (ii) an amide reaction product of a hydroxy acid, hydroxy ester, or lactone and an amine or ether amine, wherein a weight ratio of (i) to (ii) in the synergistic fuel additive mixture ranges from about 1:5 to about 5:1.
A further embodiment provides a method for reducing wear of a gasoline engine. The method includes providing gasoline containing a wear reducing additive mixture consisting essentially of (i) N,N-bis(hydroxyalkyl)-alkylamine, and (ii) an amide reaction product of a hydroxy acid, hydroxy ester, or lactone and an amine or ether amine, wherein a weight ratio of (i) to (ii) in the additive mixture ranges from about 1:5 to about 5:1; combining the additive mixture with gasoline to provide a fuel composition; and operating the engine on the fuel composition.
As set forth above, a fuel additive composition containing each of the components alone may not be stable at low temperatures. Thus it was surprising and quite unexpected that the mixture of components (i) and (ii) described above would provide a stable additive composition that remains liquid at low temperature and also provide a synergistic improvement in wear reduction of a fuel composition containing the additive mixture. The additive mixture also provides suitable fuel economy increase that is at least as good, if not better than the fuel economy increase provided by the individual components.
In a further embodiment, the fuel composition contains from about 10 to about 1500 ppm by weight, such as from about 40 to about 750 ppm by weight, or from about 50 to about 500 ppm by weight, or from about 50 to about 300 ppm by weight of the synergistic additive mixture.
Additional embodiments and advantages of the disclosure will be set forth in part in the detailed description which follows, and/or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.